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Nature. 2017 Oct 26;550(7677):487-491. doi: 10.1038/nature24043. Epub 2017 Oct 11.

Structural phase transition in monolayer MoTe2 driven by electrostatic doping.

Author information

1
NSF Nanoscale Science and Engineering Center (NSEC), 3112 Etcheverry Hall, University of California, Berkeley, California 94720, USA.
2
Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA.
3
Materials Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA.
4
Kavli Energy NanoSciences Institute and Department of Physics, University of California, Berkeley, California 94720, USA.
5
Department of Physics, King Abdulaziz University, Jeddah 21589, Saudi Arabia.

Abstract

Monolayers of transition-metal dichalcogenides (TMDs) exhibit numerous crystal phases with distinct structures, symmetries and physical properties. Exploring the physics of transitions between these different structural phases in two dimensions may provide a means of switching material properties, with implications for potential applications. Structural phase transitions in TMDs have so far been induced by thermal or chemical means; purely electrostatic control over crystal phases through electrostatic doping was recently proposed as a theoretical possibility, but has not yet been realized. Here we report the experimental demonstration of an electrostatic-doping-driven phase transition between the hexagonal and monoclinic phases of monolayer molybdenum ditelluride (MoTe2). We find that the phase transition shows a hysteretic loop in Raman spectra, and can be reversed by increasing or decreasing the gate voltage. We also combine second-harmonic generation spectroscopy with polarization-resolved Raman spectroscopy to show that the induced monoclinic phase preserves the crystal orientation of the original hexagonal phase. Moreover, this structural phase transition occurs simultaneously across the whole sample. This electrostatic-doping control of structural phase transition opens up new possibilities for developing phase-change devices based on atomically thin membranes.

PMID:
29019982
DOI:
10.1038/nature24043

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